LUBRICANT DETERIORATION DETECTING DEVICE AND DETECTING DEVICE INCORPORATED BEARING ASSEMBLY
To provide a lubricant deterioration detecting device having a high degree of freedom in arranging within the bearing assembly or the like and capable of stably detecting the status of deterioration of the lubricant without being affected by the thickness of the lubricant and a change in temperature and also to provide a detector incorporated bearing assembly equipped with such lubricant deterioration detecting device, the lubricant deterioration detecting device includes a light source, a plurality of light detecting components for detecting rays of light emitted from the light source and subsequently transmitted through a lubricant, and a determining unit. The plural light detecting components have respective light detecting faces sequentially displaced in position. The determining unit compares respective signal strengths of outputs from the plural light detecting components to detect the status of deterioration of the lubricant.
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1. Field of the Invention
The present invention relates to a lubricant deterioration detecting device for detecting the status of deterioration of a lubricant resulting from admixture of an alien substance and also to a detecting device incorporated bearing assembly equipped with such lubricant detection detecting device such as, for example, a detector incorporated bearing assembly for use in railway vehicles, automotive vehicles and industrial machines or the like.
2. Description of the Prior Art
In the bearing assembly filled with a lubricant, an insufficient lubrication occurs once the lubricant (such as, for example, a grease or oil) within the bearing assembly is deteriorated, resulting in a reduction in lifetime of the bearing assembly. Since determination of the occurrence of the insufficient lubrication in reference to the status of vibration or the like occurring in the bearing assembly is carried out when and after an operating abnormality has occurred as a result of expiration of the lifetime of the bearing assembly, the presence or absence of an abnormality in lubrication cannot be carried out at an early time. In view of this, it has been desired to monitor the status of the lubricant within the bearing assembly regularly or in real time so that the occurrence of the abnormality and/or the time for maintenance can be predicated.
A major cause of deterioration of the lubricant may include an admixture of powdery wear debris, which is produced as the bearing assembly is used, into the lubricant.
For detecting the status of wear of the bearing assembly, a sensor incorporated bearing assembly has been suggested, in which a sensor in the form of an electrode or a coil is arranged inside a sealing member of the bearing assembly so that the electrical characteristic of the lubricant resulting from the admixture of the wear debris can be detected. (See, for example, the Japanese Laid-open Patent Publication No. 2004-293776, published Oct. 21, 2004.)
However, since the sensor incorporated bearing assembly disclosed in the above mentioned patent document is so designed that the electrical characteristic of the lubricant can be detected, no change in characteristic can be detected unless a condition is established in which conduction occurs as a result of inclusion of a substantial amount of wear debris, and thus, difficulty often occurs in detecting the inclusion of the alien substance.
In order to alleviate the problems discussed above, such an optical construction, although it has not yet been known, has been contemplated, in which, for example, as shown in
In the case of the above described construction, it has been found that where the thickness d of the lubricant 55 forming an object to be detected changes as shown by the broken line in
In view of the above, such an alternative construction, although it has also not yet been known, has been contemplated, in which, for example, as shown in
With the construction shown in
However, even with the construction shown in
An object of the present invention is to provide a lubricant deterioration detecting device having a high degree of freedom in arranging within the bearing assembly or the like and capable of stably detecting the status of deterioration of the lubricant without being affected by the thickness of the lubricant and a change in temperature and also to provide a detecting device incorporated bearing assembly equipped with such lubricant deterioration detecting device.
The lubricant deterioration detecting device of the present invention includes a light source, a plurality of light detecting components for detecting rays of light emitted from the light source and subsequently transmitted through a lubricant, and a determining unit for detecting the status of deterioration of the lubricant. The plural light detecting components have respective light detecting faces sequentially displaced in position, and the determining unit is operable to compare respective signal strengths of outputs from the plural light detecting components.
As described above, since this lubricant deterioration detecting device is so designed that while the plural light detecting components are arranged, for example, in line with their light detecting faces sequentially displaced in position, the status of deterioration of the lubricant can be detected when the signal strengths of the outputs of those light detecting components are compared with each other by the determining unit, the status of deterioration of the lubricant can be detected without being affected by the thickness of the lubricant itself, the intensity of light emitted from the light source and the distance between the light source and the light detecting components, when such detection is made with the plural light detecting components arranged in the lubricant.
As a result, even where the lubricant deterioration detecting device is arranged within the bearing assembly, a large freedom of arrangement is available and construction is possible to accommodate to the limited available space for installation. Considering that the status of deterioration of the lubricant is detected by comparing the respective signal strengths of the outputs of the plural light detecting components, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. Also, arrangement of the light detecting components within the lubricant is effective in that influences brought about by a temperature dependent change in characteristic can be counterbalanced among the plural light detecting components and, accordingly, a highly accurate detection can be accomplished.
In the present invention, the determining unit referred to above may be of a type capable of estimating an amount of the alien substance admixed into the lubricant through comparison of the signal strengths referred to above.
By way of example, where the lubricant is filled within the bearing assembly, foreign matter such as, for example, powdery wear debris is trapped into the lubricant as the bearing assembly is used in practice and, therefore, a detection output of the determining unit becomes low as the amount of the alien substance admixed increases. Accordingly, the amount of the alien substance admixed into the lubricant can be estimated from the value of the detection output of the determining unit. On the other hand, since increase of the amount of the alien substance admixed means a progress of deterioration of the lubricant, the determining unit can detect the status of lubricant from the estimated amount of the alien substance admixed.
In the present invention, each of the light detecting components referred to above may include a detector and a light guide element having one end in the form of a base end connected with the detector and the other end in the form of a free end forming the light detecting face. Since even in this construction, the plural light detecting components have their detecting faces sequentially displaced in position, the status of deterioration of the lubricant can be detected without being affected by the thickness of the lubricant itself, the intensity of the light source and the distance between the light source and the light detecting components.
In the present invention, each of the light detecting components referred to above may include a detector and an optical fiber having one end in the form of a base end connected with the detector and the other end in the form of a free end forming the light detecting face. Where the optical fibers are employed, a detecting site, where the plural light detecting components are arranged, can have a reduced thickness and, therefore, the lubricant can be allowed to enter the detecting site easily and a stable detection can be accomplished accordingly.
In the present invention, the light source may be in the form of a linear-shaped light source. Where the light source is in a line shape, the intensity of light incident on the detecting site comes to be uniform regardless of the position and, therefore, a stable detection is possible.
In the present invention, the determining unit referred to above may be of a type capable of calculating a light transmittance of the lubricant. Since the light transmittance of the lubricant attenuates as the deterioration of the lubricant proceeds accompanied by, for example, an increase of the amount of the alien substance admixed within the lubricant, calculation of the light transmittance of the lubricant can lead to detection of the status of deterioration of the lubricant.
In the present invention, the determining unit includes a selector section for excluding, from the output signals of the plural light detecting components, output signals of a light detecting components which generate a saturated output, and output signals of light detecting components indicative of a detected light intensity not attaining a predetermined value, in order to use respective output signals of the rest of the light detecting components for detection of the status of deterioration of the lubricant.
It may occur that depending on the intensity of light emitted from the light source, some of the light detecting components may generate a saturated output or generate no output. However, even in such case, it is possible to select, by means of the selector section, comparison output of the light detecting components then generating a proper output and then to assuredly detect the status of deterioration of the lubricant from a broad range of locations.
The lubricant deterioration detecting device of the present invention may include two light detecting components of the kind referred to above.
According to the lubricant deterioration detecting device of the construction described above, rays of light from the light source are attenuated before they reach the light detecting components as they are absorbed and/or scattered on the way, and the intensity of such light is detected by the first light detecting components. When using as reference, the output of the second light detecting component to which light arrives first, the output of the second light detecting component is evaluated, it is possible to detect the amount of light attenuated due to the distance between the two light detecting components. In this way, since construction is employed, in which the amount of light attenuated due to the distance between the two light detecting components can be detected, if the spacing between the light detecting components is fixed, measurement, which does not depend on the distance from the light source and the intensity of the light source, can be accomplished. Accordingly, if this output difference is used, estimation of the status of deterioration of the lubricant, for example, the amount of, for example, alien substance, generated as a result of frictional wear, admixed can be estimated without being adversely affected by, for example, the thickness of the lubricant.
Since the distance between the light source and the light detecting components need not be fixed, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited space available for installation. Also, because of the construction in which the signal strengths of the two light detecting components are compared to achieve the detection, a stable detection can be accomplished without adversely affected by common mode noises such as variation in electric power supply. Even though the two light detecting components are arranged within the lubricant, changes in characteristic resulting from change in temperature between the two light detecting components can be counterbalanced and, hence, an accurate detection can be accomplished.
In the present invention, a temperature sensor may be provided at a position in proximity to the light detecting components. In the case of this construction, by allowing the temperature sensor to monitor the temperatures of the lubricant and the light detecting components, correction appropriate to the temperature dependent change can be applied to the detection result. Accordingly, a further accurate detection can be accomplished and the possibility that a change in detected signal resulting from a change in ambient temperature would be erroneously determined as resulting from the deterioration of the lubricant can be avoided.
In the lubricant deterioration detecting device according to the present invention, a light amount adjusting unit may be provided for adjusting an amount of light of the light source so that an output of one of the two light detecting components, which is closest the light source, attains a predetermined constant value.
With the lubricant deterioration detecting device of the construction described above, even though the amount of light received is likely to overflow or underflow as a result of a considerable change in thickness of the lubricant 6 and/or in light transmittance, the light amount adjusting unit automatically adjusts the amount of light of the light source so that the output of the light detecting component can attain a predetermined constant value and, accordingly, a stabilized detection can be accomplished. Accordingly, when the difference between the respective outputs of the two light detecting components is used, estimation of the status of deterioration of the lubricant, for example, estimation of the amount of the alien substance, generated as a result of, for example, frictional wear, which is admixed can be accomplished.
Since the distance between the light source and the light detecting components need not be fixed, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited space limited space available for installation. Also, because of the construction in which the signal strengths of the two light detecting components are compared to achieve the detection, a stable detection can be accomplished without adversely affected by common mode noises such as variation in electric power supply. Even though the two light detecting components are arranged within the lubricant, changes in characteristic resulting from change in temperature between the two light detecting components can be counterbalanced and, hence, an accurate detection can be accomplished.
In the lubricant deterioration detecting device according to the present invention, a light amount adjusting unit may be provided for adjusting an amount of light of the light source so that an output of one of the two light detecting components, which is remotest from the light source, attains a predetermined constant value.
Even with the lubricant deterioration detecting device of the construction described above, effects similar to those afforded by the lubricant deterioration detecting device according to the above described invention can be obtained.
In the lubricant deterioration detecting device of the present invention, an amplifying unit for amplifying an output of each of the light detecting components and a unit for adjusting a gain of the amplifying unit may be provided, in which case the determining unit compares the outputs amplified by the amplifying unit to detect the status of deterioration of the lubricant and wherein the gain adjusting unit adjusts a gain of the amplifying unit to allow the output of each of the light detecting components, which has been amplified by the amplifying unit, to attain a value within a predetermined range.
According to the lubricant deterioration detecting device of the construction described above, even though the outputs of the light detecting components amplified by the amplifying unit are likely to overflow or underflow as a result of a considerable change in thickness of the lubricant and/or in light transmittance, the gain adjusting unit adjusts the gain of the amplifying unit and, accordingly, a stable measurement can be accomplished. Accordingly, when the difference between the respective outputs of the two light detecting components is used, estimation of the status of deterioration of the lubricant, for example, estimation of the amount of the alien substance, generated as a result of, for example, frictional wear, which is admixed can be accomplished.
Since the distance between the light source and the light detecting components need not be fixed, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited space available for installation. Also, because of the construction in which the signal strengths of the two light detecting components are compared to achieve the detection, a stable detection can be accomplished without adversely affected by common mode noises such as variation in electric power supply. Even though the two light detecting components are arranged within the lubricant, changes in characteristic resulting from change in temperature between the two light detecting components can be counterbalanced and, hence, an accurate detection can be accomplished.
In the lubricant deterioration detecting device of the present invention, two light detecting components are provided therein and each of the light detecting components may include a detector and a optical fiber bundle having one end in the form of a base end connected with the detector and the other end in the form of a free end forming a light detecting face.
According to this construction, the amount of light attenuated after having passed across the thickness of the sample, which corresponds to the displacement in position of the free ends of the two bundles of optical fibers, can be detected by comparison of the signal outputs from the two detectors. For this reason, without being adversely affected by the thickness of the sample itself, the amount of the sample, the intensity of the light source and the distance from the light source to the light detectors, the light transmittance of the sample can be stably and accurately detected. As a result thereof, even when the transmittance detecting device is incorporated in, for example, the bearing assembly or the like, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited available space for installation. Also, considering that the status of deterioration of the lubricant 6 is detected by comparing the respective signal outputs of the light detectors, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. In addition, since the optical fibers are employed and since a sufficient light receiving surface area can be secured on the light receiving side, not only can the intensity of received light be obtained with the light detectors, but also any variation in thickness of the sample depending on the position can be cancelled and, hence, even in this respect, the light transmittance can be stably measured.
In the lubricant deterioration detecting device including the optical fiber bundles described above, a temperature sensor may be positioned proximate to the free ends of the optical fiber bundles, in which case, the use may be made of a correcting unit for correcting an output of the determining unit based on a detected value of the temperature sensor. In the case of this construction, the possibility that a change in detected signal resulting from a change in ambient temperature would be erroneously determined as resulting from the deterioration of the lubricant can be avoided.
In the lubricant deterioration detecting device including the optical fiber bundles as described above, each of the respective free ends of the optical fiber bundles may be arranged in line. In the case of this construction, since the light receiving unit can have a thin structure, deterioration of the lubricant distributed in a planar shape can be detected effectively.
In the lubricant deterioration detecting device including the bundles of optical fibers, the light source may be in the form of a linear-shaped light source corresponding to a line shaped arrangement of the free ends of the bundles of optical fibers. If the light source is employed in the form of a linear-shaped light source, the light receiving efficiency can be increased.
In the lubricant deterioration detecting device including the bundles of optical fiber, the optical fiber bundles have respective free end faces planarly arranged. The light source is preferably a planar light source corresponding to the planar shape in which the free ends of the bundle of optical fibers are arranged. In the case of this construction, averaging can be made even though the distribution of thickness of the lubricant varies and, therefore, a stable measurement can be accomplished without such variation adversely affecting the measured value. Also, merely positioning of the light source in face-to-face relation with the bundled optical fiber array having the lubricant 6 deposited on the free end face thereof makes it possible to accomplish the stabilized measurement.
A detecting device incorporated bearing assembly of the present invention is of a type in which the lubricant deterioration detecting device of any one of the constructions described above in accordance with the present invention is mounted.
According to this construction, deterioration of the lubricant filled within the bearing unit can be accurately detected in real time or regularly. As a result, prior to an actual occurrence of an abnormality in the bearing device, the necessity of replacement of the lubricant can be judged and it is possible to prevent the bearing device from being damaged as a result of the defective lubricant. Also, since the necessity of replacement of the lubricant can be determined in reference to the output of the lubricant deterioration detecting device, the amount of the lubricant which may be discarded prior to the lifetime of use can be reduced.
In any event, the present invention will become more clearly understood from the following description of preferred embodiments thereof, when taken in conjunction with the accompanying drawings. However, the embodiments and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several views, and:
A first preferred embodiment of the present invention will be described with particular reference to
In this embodiment, each of the light detecting components 3 is made up of a detector 11A and a light guide element 11B having one end in the form of a base end connected with the detector 11A and the other end in the form of a free end forming the light detecting face referred to above. The detectors 11A are formed in an array in which they are arranged in the same position relative to the direction of travel of the rays of light. In contrast thereto, the light guide elements 11B have varying lengths so that the free ends thereof occupy respective positions sequentially displaced a predetermined distance d relative to the direction of travel of the rays of light. In this way, the respective positions of the light detecting faces of the plural light detecting components are sequentially displaced the predetermined distance d relative to the direction of travel of the rays of light. For the detector 11A, a photodiode, a phototransistor, a CDS, a solar cell or a photomultiplier may be employed. Each of the light guide elements 11B is made of a transparent material such as, for example, a cylindrical synthetic resin or glass and the free end thereof, which defines the light detecting face, represents a transparent round window, and an outer peripheral surface of each of the light guide elements 11B is coated with a reflective material so that the rays of light incident on the corresponding light detecting face can travel therethrough towards the associated detector 11A.
It is to be noted that for each of the light guide elements 11B, an optical fiber may be employed. In the case that the optical fibers are employed, a detecting site, where the plural light detecting components 3 are arranged, can be thinned and, therefore, ingress of the lubricant 6 into the detecting site can be facilitated to accomplish a stabilized detection.
Also, in correspondence with the light detecting components 3 arranged in line, the light source 2 is preferably in the form of a linear-shaped light source. Where the light source 2 is in the form of the linear-shaped light source in correspondence with the line arrangement of the light detecting components 3, the intensity of light incident on the detecting site becomes uniform regardless of the position and, therefore, a stable detection can be accomplished. For the light source 2, an LED, an incandescent bulb, a semiconductor laser diode, an EL, an organic EL or a fluorescent tube may be employed.
The determining unit 5 includes a determining section 14 and a selecting section 15 as shown in
It occurs that depending on the intensity of light emitted from the light source 2, some of the light detecting components 3 may generate a saturated output or no output. Even in such case, the comparison output from the light detecting components 3 that have generated a proper output can be selected by the selecting section 15 and, therefore, the status of deterioration of the lubricant 6 can be detected assuredly.
It is to be noted that although in
In the lubricant deterioration detecting device 1 of the construction described hereinabove, the intensity of light transmitted through the lubricant 6 attenuates considerably depending on the distance over which the rays of light travel. The relation between the intensity of the transmitted light and the light transmitting distance is shown in the chart of
I=Iinexp(−αx) (1)
Hence, the respective signal strengths I0 and I1 of the outputs of the neighboring light detecting components 3 having light detecting faces which are held at respective locations spaced distances x0 and x1, is expressed by the following equations (2) and (3):
I0=Iinexp(−αx0) (2)
I=Iinexp(−αx1) (3)
Where the determining unit 5 is of a type capable of determining the ratio of the respective signal strengths of the outputs of the neighboring light detecting components 3 that are displaced a distance d from each other, a detected output of the determining unit 5 is expressed by the following equation (4):
(I1/I0)=exp(−α(x1−x0))=exp(−αd) (4)
In other words, the detected output of the determining unit 5 is a value dependent on the distance d of the light detecting faces of the neighboring light detecting components 3 regardless of the thickness of the lubricant 6 itself. Since this relation establishes among the light detecting components 3 that are arrayed, the detected output of the determining unit 5 may be secured using outputs of any of the light detecting components 3.
Also, the constant α in the equation (4) above varies depending on the status of the lubricant 6. By way of example, where the lubricant 6 is of a kind filled in the bearing assembly, foreign matter such as, for example, powdery wear debris are admixed into the lubricant 6 as the bearing assembly is used in practice, and the constant α increases with an increase of the amount of the alien substance admixed. Accordingly, in the case where the determining unit 5 determines the ratio of the signal strengths of the neighboring light detecting components 3 that are displaced the distance d from each other as hereinabove described, the light transmittance of light having traveled along an optical path of the distance d in the lubricant 6 is detected and, hence, it is possible to estimate from the value of the detected output the amount of the alien substance admixed into the lubricant 6. Also, since an increase of the amount of the alien substance admixed means a progress of deterioration taking place in the lubricant 6, the determining unit 5 can detect the status of deterioration of the lubricant 6 from the amount of the alien substance estimated.
It is to be noted that the determining unit 5 referred to above may be of a type capable of determining the difference between the signal strengths of the neighboring detecting elements 3 that are displaced the distance d from each other. Since even in such case the determining unit 5 determines the light transmittance of the light transmitted the distance d in the lubricant 6, the amount of the alien substance admixed into the lubricant 6 can be estimated from the detected output thereof and, in turn, the status of deterioration of the lubricant 6 can be detected from the estimated amount of the alien substance admixed.
As hereinabove described, this lubricant deterioration detecting device 1 is so designed and so configured that while the plural light detecting components 3 are arranged with their light detecting faces held displaced the distance d from each other relative to the direction of travel of rays of light, the signal strengths of the outputs of the neighboring light detecting components 3 can be compared by the determining unit 5 to detect the status of deterioration of the lubricant 6. Accordingly, the status of deterioration of the lubricant 6 can be detected without being adversely affected by the thickness of the lubricant 6 itself, the intensity of the light source 2, and/or the distance from the light source 2 to the light detecting components 3.
Also, even in the case where, in view of the plural light detecting components 3 arranged, some of the light detecting components 3 generate a saturated output or no output depending on the intensity of light, the selecting section 15 of the determining unit 5 can select, out of a plurality of detection results generated by the determining section 14 of the determining unit 5, respective comparison outputs of each of the sets of the neighboring light detecting components 3 that provide a proper output to enable a assured detection of the status of deterioration of the lubricant 5 from a broad range of locations.
As a result, even when the lubricant deterioration detecting device 1 is incorporated in, for example, the bearing assembly or the like, degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited available space for installation. Also, considering that the status of deterioration of the lubricant 6 is detected by comparing the respective signal strengths of the outputs of the plural light detecting components 3, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. In addition, arrangement of the light detecting components 3 within the lubricant 6 is effective in that influences brought about by a temperature dependent change in characteristic can be counterbalanced among the neighboring light detecting components 3 and, accordingly, a highly accurate detection can be accomplished.
It is to be noted that in the construction described above, arrangement may be made that the result of detection can be made based on a change in temperature by disposing a temperature sensor in proximity of the light detecting components 3 for monitoring the temperatures of the lubricant 6 and the light detecting components 3. More specifically, for example, a circuit may be employed for correcting the detection signal generated at the temperature measured at the time of actual use, if a change in detection signal with change in temperature is beforehand measured. In such case, by sensing the temperature of the lubricant 6, it is possible to avoid the possibility that a change in detection signal with change in ambient temperature would be erroneously determined as resulting from deterioration of the lubricant 6. In this way, an accurate detection can be accomplished.
Also, in the construction described above, the determining unit 5 may include a comparing circuit for comparing a detection signal, which is obtained by comparing the respective signal strengths of the outputs from the neighboring light detecting components 3 with each other, with a predetermined reference value. In such case, the status of deterioration of the lubricant 6 can be easily determined as exceeding a predetermined level and, accordingly, it can be used as an indication of the time of replacement.
Where the lubricant deterioration detecting device 1 is so constructed as hereinabove described, the status of deterioration of the lubricant 6 entering in the groove 18 and distributed on the flat can be detected.
It is to be noted that although in the embodiment shown in
A second preferred embodiment of the present invention will be described with particular reference to
For the light source 2, an LED, an incandescent bulb, a semiconductor laser diode, an EL, an organic EL or a fluorescent tube may be employed. Also, for each of the light detecting components 3 and 4, a photodiode, a phototransistor, a CDS, a solar cell or a photomultiplier may be employed. In
Also, the constant α in the equation (4) described previously varies depending on the status of the lubricant 6. By way of example, where the lubricant 6 is of a kind filled in the bearing assembly, foreign matter such as, for example, powdery wear debris are admixed into the lubricant 6 as the bearing assembly is used in practice and, accordingly, the constant α increases with an increase of the amount of the alien substance admixed. Therefore, in the case where the determining unit 5 determines the ratio of the signal strengths of the light detecting components 3 and 4 as hereinabove described, the light transmittance of light having traveled the distance d within the lubricant 6 is detected and, hence, it is possible to estimate from the value of the detected output the amount of the alien substance admixed into the lubricant 6. Also, since an increase of the amount of the alien substance admixed means a progress of deterioration taking place in the lubricant 6, the determining unit 5 can detect the status of deterioration of the lubricant 6 from the amount of the alien substance estimated.
It is to be noted that the determining unit 5 may be of a type capable of determining the difference between the respective signal strengths of the two light detecting components 3 and 4. Even in this case, the determining unit 5 detects the light transmittance of rays of light transmitted the distance d within the lubricant 6 and, accordingly, the amount of the alien substance admixed into the lubricant 6 can be estimated from the detected output thereof and the status of deterioration of the lubricant 6 can accordingly detected from the amount of the alien substances so estimated.
As hereinabove described, this lubricant deterioration detecting device 1 is so designed that the two light detecting components 3 and 4 are arranged with their light detecting faces displaced from each other the distance d relative to the direction of travel of the rays of light so that the respective signal strengths of the outputs of the two light detecting components 3 and 4 can be compared by the determining unit 5 to detect the status of deterioration of the lubricant 6. Accordingly, the status of deterioration of the lubricant 6 can be detected without being adversely affected by the thickness of the lubricant 6 itself, the intensity of the light source 2 and/or the distance from the light source 2 to the light detecting components 3 and 4.
As a result, even when the lubricant deterioration detecting device 1 is incorporated in, for example, the bearing assembly or the like, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited available space for installation. Also, considering that the status of deterioration of the lubricant 6 is detected by comparing the respective signal strengths of the outputs of the light detecting components 3 and 4, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. In addition, arrangement of the light detecting components 3 and 4 within the lubricant 6 is effective in that influences brought about by a temperature dependent change in characteristic of those two light detecting components 3 and 4 can be counterbalanced and, accordingly, a highly accurate detection can be accomplished.
It is to be noted that in the construction described above, arrangement may be made that the result of detection can be made based on a change in temperature by disposing a temperature sensor in proximity of the two light detecting components 3 and 4 for monitoring the temperatures of the lubricant 6 and the light detecting components 3 and 4. More specifically, for example, a circuit may be employed for correcting the detection signal generated at the temperature measured at the time of actual use, if a change in detection signal with change in temperature is beforehand measured. In such case, by sensing the temperature of the lubricant 6, it is possible to avoid the possibility that a change in detection signal with change in ambient temperature would be erroneously determined as resulting from deterioration of the lubricant 6. In this way, an accurate detection can be accomplished.
Also, in the construction described above, the determining unit 5 may include a comparing circuit for comparing a detection signal, which is obtained by comparing the respective signal strengths of the outputs from the two light detecting components 3 and 4 with each other, with a predetermined reference value. In such case, the status of deterioration of the lubricant 6 can be easily determined as exceeding a predetermined level and, accordingly, it can be used as an indication of the time of replacement.
Even in the case of the lubricant deterioration detecting device 1, since the two light detecting components 3 and 4 are so arranged as to have their light detecting faces held displaced the distance d from each other relative to the direction of travel of the rays of light, the status of deterioration of the lubricant 6 can be detected without being adversely affected by thickness of the lubricant 6 itself, the intensity of the light source 2 and/or the distance from the light source 2 to the light detecting components 3 and 4.
Even in the case of the lubricant deterioration detecting device 1, since the two light detecting components 3 and 4 are so arranged as to have their light detecting faces held displaced the distance d from each other relative to the direction of travel of the rays of light, the status of deterioration of the lubricant 6 can be detected without being adversely affected by thickness of the lubricant 6 itself, the intensity of the light source 2 and/or the distance from the light source to the light detecting components 3 and 4.
A fifth preferred embodiment of the present invention will now be described with particular reference to
For the light source 2, an LED, an incandescent bulb, a semiconductor laser diode, an EL, an organic EL or a fluorescent tube may be employed. Also, for each of the light detecting components 3 and 4, a photodiode, a phototransistor, a CDS, a solar cell or a photomultiplier may be employed. In
The light amount adjusting unit 7 is operable to adjust the amount of light emitted from the light source 2 so that an output of one of the two light detecting components 3 and 4 that is closest to the light source 2, that is, an output of the light detecting component 3 (or the amount of light incident on the light detecting component 3) can represent a predetermined proper constant value (or a value within a constant range) by judging based on an output of the light detecting component 3. In this case, the proper constant value (or the value within the constant range) represented by the output of the light detecting component 3 means a value representing proper output of the light detecting component 3 corresponding to the amount of light received thereby without being saturated. It is to be noted that the amount of light received by the light detecting component 4 remote from the light source 2 does not exceed the amount of light received by the light detected element 3 closest to the light source 2 and, therefore, by setting the output of the light detecting component 3 to a value as large as possible unless saturated, a highly precise detecting system can be obtained.
The light amount adjusting unit may be composed of either an electronic circuit or that having a calculator or a built-in computer. Also, adjustment of the amount of light of the light source 2 accomplished by the light amount adjusting unit 7 may be performed either automatically continuously or intermittently only at the time of detection for the status of deterioration of the lubricant 6. In addition, where heat evolution of the light source 2 is requested to be suppressed or the maximum amount of light is desired to be increased, it is preferred that the light source 2 may be lit only at the time of detection of the status of deterioration of the lubricant 6, instead of being lit continuously.
Also, the constant α in the equation (4) above varies depending on the status of the lubricant 6. By way of example, where the lubricant 6 is of a kind filled in the bearing assembly, foreign matter such as, for example, powdery wear debris are admixed into the lubricant 6 as the bearing assembly is used in practice, the constant α increases with an increase of the amount of the alien substance admixed. Accordingly, in the case where the determining unit 5 determines the ratio of the signal strengths of the two light detecting components 3 and 4 as hereinabove described, the light transmittance of light having traveled along an optical path of the distance d in the lubricant 6 is detected and, hence, it is possible to estimate from the value of the detected output the amount of the alien substance admixed into the lubricant 6. Also, since an increase of the amount of the alien substance admixed means a progress of deterioration taking place in the lubricant 6, the determining unit 5 can detect the status of deterioration of the lubricant 6 from the amount of the alien substance estimated.
It is to be noted that the determining unit 5 referred to above may be of a type capable of determining the difference between the signal strengths of the two detecting elements 3 and 4 referred to above. Since even in such case the determining unit 5 determines the light transmittance of the light transmitted the distance d in the lubricant 6, the amount of the alien substance admixed into the lubricant 6 can be estimated from the detected output thereof and, in turn, the status of deterioration of the lubricant 6 can be detected from the estimated amount of the alien substance admixed.
Also, even though the amount of light received is likely to overflow or underflow as a result of a considerable change in thickness of the lubricant 6 and/or in light transmittance, the light amount adjusting unit 7 automatically adjusts the amount of light of the light source 2 (to allow the output of the light detecting component 4 to attain a proper value) so that the output of the light detecting component 3 can attain a predetermined proper constant value (or a value within the constant range) and, accordingly, a stabilized detection can be accomplished.
As hereinabove described, this lubricant deterioration detecting device 1 is so designed and so configured that while the two light detecting components 3 and 4 are arranged with their light detecting faces held displaced the distance d from each other relative to the direction of travel of rays of light, the signal strengths of the outputs of the two light detecting components 3 and 4 can be compared by the determining unit 5 to detect the status of deterioration of the lubricant 6, and the amount of light of the light source 2 is automatically adjusted by the light amount adjusting unit 7. Accordingly the status of deterioration of the lubricant 6 can be detected without being adversely affected by the thickness of the lubricant 6 itself, the intensity of the light source 2 and/or the distance from the light source 2 to the light detecting components 3.
As a result, even when the lubricant deterioration detecting device 1 is incorporated in, for example, the bearing assembly or the like, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited available space for installation. Also, considering that the status of deterioration of the lubricant 6 is detected by comparing the respective signal strengths of the outputs of the two light detecting components 3 and 4, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. In addition, arrangement of the two light detecting components 3 and 4 within the lubricant 6 is effective in that influences brought about by a temperature dependent change in characteristic can be counterbalanced among the two light detecting components 3 and 4 and, accordingly, a highly accurate detection can be accomplished.
It is to be noted that in the construction described above, arrangement may be made that the result of detection can be made based on a change in temperature by disposing a temperature sensor in proximity of the light detecting components 3 and 4 for monitoring the temperatures of the lubricant 6 and the light detecting components 3 and 4. More specifically, for example, a circuit may be employed for correcting the detection signal generated at the temperature measured at the time of actual use, if a change in detection signal with change in temperature is beforehand measured. In such case, by sensing the temperature of the lubricant 6, it is possible to avoid the possibility that a change in detection signal with change in ambient temperature would be erroneously determined as resulting from deterioration of the lubricant 6. In this way, an accurate detection can be accomplished.
Also, in the construction described above, the determining unit 5 may include a comparing circuit for comparing a detection signal, which is obtained by comparing the respective signal strengths of the outputs from the two light detecting components 3 and 4 with each other, with a predetermined reference value. In such case, the status of deterioration of the lubricant 6 can be easily determined as exceeding a predetermined level and, accordingly, it can be used as an indication of the time of replacement.
Even in the case of the lubricant deterioration detecting device 1 of the construction described above, since the two light detecting components 3 and 4 are arranged with their light detecting faces displaced from each other the distance d relative to the direction of travel of the rays of light, the status of deterioration of the lubricant 6 can be detected without being adversely affected by the thickness of the lubricant 6 itself the intensity of the light source 2 and/or the distance from the light source 2 to the light detecting components 3 and 4.
It is to be noted that in this embodiment, the light amount adjusting unit 7 may be so designed as to adjust the amount of light of the light source 2 based on the output of the light detecting component 4, that is remotest from the light source 2.
Even in the case of the lubricant deterioration detecting device 1, since the two light detecting components 3 and 4 are so arranged as to have their light detecting faces held displaced the distance d from each other relative to the direction of travel of the rays of light, the status of deterioration of the lubricant 6 can be detected without being adversely affected by thickness and/or light transmittance of the lubricant 6 itself, the intensity of the light source 2 and/or the distance from the light source to the light detecting components 3 and 4.
A ninth preferred embodiment of the present invention will now be described with particular reference to
For the light source 2, an LED, an incandescent bulb, a semiconductor laser diode, an EL, an organic EL or a fluorescent tube may be employed. Also, for each of the light detecting components 3 and 4, a photodiode, a phototransistor, a CDS, a solar cell or a photomultiplier may be employed. In
Each of the gain adjusting units 24 and 25 is operable to adjust the gain of the associated amplifying units 20 and 21 so that the output of the respective light detecting component 3 and 4 can attain a value within a predetermined range.
In this way, this constructional example can have a function equivalent to the switching performed by the switch 27 in any one of the constructional examples hereinabove described. In such case, a change of the gain of the voltage controlled amplifier 29 may be in a multi-step fashion or a non-step fashion. The constant α in the equation (4) described previously varies depending on the status of the lubricant 6. By way of example, where the lubricant 6 is of a kind filled in the bearing assembly, foreign matter such as, for example, powdery wear debris are admixed into the lubricant 6 as the bearing assembly is used in practice and, accordingly, the constant α increases with an increase of the amount of the alien substance admixed. Therefore, in the case where the amplifying units 20 and 21 have the same gain and the determining unit 5 determines the ratio of the signal strengths of the respective outputs of the light detecting components 3 and 4, which have been amplified by the amplifying units 20 and 21, the light transmittance of light having traveled the distance d within the lubricant 6 is detected and, hence, it is possible to estimate from the value of the detected output the amount of the alien substance admixed into the lubricant 6. Also, since an increase of the amount of the alien substance admixed means a progress of deterioration taking place in the lubricant 6, the determining unit 5 can detect the status of deterioration of the lubricant 6 from the amount of the alien substance estimated.
It is to be noted that the determining unit 5 may be of a type capable of determining the difference between the respective signal strengths of the outputs of the two light detecting components 3 and 4 which have been amplified by the amplifying units 20 and 21. Even in this case, the determining unit detects the light transmittance of rays of light transmitted the distance d within the lubricant 6 and, accordingly, the amount of the alien substance admixed into the lubricant 6 can be estimated from the detected output thereof and the status of deterioration of the lubricant 6 can accordingly detected from the amount of the alien substances so estimated.
In this lubricant deterioration detecting device 1, in the case where, for example, the thickness of the lubricant 6 is so small, the light transmittance is so large, the intensity of the light source 2 is so large, or the distance from the light source 2 to the light detecting component 3 is so small that the output of the light detecting component 3 may represent a value exceeding the value within the predetermined range, the gain adjusting unit 24 lowers the gain of the amplifying unit 20. Accordingly, the output of the light detecting component 3 amplified by the amplifying unit 20 can be adjusted to attain the value within the predetermined range and is then supplied to the determining unit 5 as an output for comparison purpose. The determining unit 5 compares the output of the light detecting component 3 so adjusted in the way described above, and the value of the output of the other light detecting component 4 amplified by the amplifying unit 21 with each other to thereby detect the light transmittance of the light traveling the distance d in the lubricant 6 (the status of deterioration of the lubricant 6). In such case, during the detection process taking place in the determining unit 5, the change of the gain effected by the amplifying unit 20 is taken into consideration.
Also, it may occur that depending on the thickness of the lubricant, the light transmittance, the intensity of the light source 2, or the distance from the light source 2 to the light detecting components 3 and 4, the output of the light detecting component 3 may represent a value exceeding the value within the predetermined range and, on the other hand, the output of the other light detecting component 4 may represent a value lower than the value within the predetermined range. In such case, not only does the gain adjusting unit 24 lower the gain of the amplifying unit 20, but the gain adjusting unit 25 increases the gain of the amplifying unit 21. Accordingly, the output of the light detecting component 3 amplified by the amplifying unit 20 and the output of the light detecting component 4 amplified by the amplifying unit 21 are adjusted to represent the respective values falling within the predetermined ranges and are then supplied to the determining unit 5 for comparison purpose. The determining unit 5 then compares the respective amplified outputs of the light detecting components 3 and 4 with each other to thereby detect the light transmittance of the light traveling the distance d in the lubricant 6 (the status of deterioration of the lubricant 6). In such case, during the detection process taking place in the determining unit 5, the change of the gains effected by the amplifying units 20 and 21, respectively, are taken into consideration.
As hereinabove described, in this lubricant deterioration detecting device 1, the two light detecting components 3 and 4 are so arranged that their light detecting faces are held displaced the distance d from each other relative to the direction of travel of the rays of light, and the respective outputs of those two light detecting components 3 and 4 are, after having been amplified by the amplifying units 20 and 21, compared with each other by the determining unit 5 to thereby detect the status of deterioration of the lubricant 6. Also, the gain adjusting units 24 and 25 automatically adjust the respective gains of the amplifying units 20 and 21 so that the outputs of the light detecting components 3 and 4 amplified by the amplifying units 20 and 21, respectively, can represent values within the predetermined range. For these reasons, the status of deterioration can be stably detected without being adversely affected by the thickness of the lubricant 6 itself, the light transmittance thereof, the intensity of the light source 2 and/or the distance from the light source 2 to the light detecting components 3 and 4.
As a result, even when the lubricant deterioration detecting device 1 is incorporated in, for example, the bearing assembly or the like, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited available space for installation. Also, considering that the status of deterioration of the lubricant 6 is detected by comparing the respective outputs of the light detecting components 3 and 4, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. In addition, since the light detecting components 3 and 4 are arranged within the lubricant 6, influences brought about by a temperature dependent change in characteristic of those two light detecting components 3 and 4 can be counterbalanced and, accordingly, a highly accurate detection can be accomplished.
It is to be noted that in the construction described above, arrangement may be made that the result of detection can be made based on a change in temperature by disposing a temperature sensor in proximity of the light detecting components 3 and 4 for monitoring the temperatures of the lubricant 6 and the light detecting components 3 and 4. More specifically, for example, a circuit may be employed for correcting the detection signal generated at the temperature measured at the time of actual use, if a change in detection signal with change in temperature is beforehand measured. In such case, by sensing the temperature of the lubricant 6, it is possible to avoid the possibility that a change in detection signal with change in ambient temperature would be erroneously determined as resulting from deterioration of the lubricant 6. In this way, an accurate detection can be accomplished.
When this lubricant deterioration detecting device 1 to be operated, the amplifying units 20 and 21 may be used in the following manner depending on the signal strengths of the outputs of the light detecting components 3 and 4.
1. When the respective outputs of the light detecting components 3 and 4 are both low, those outputs of the light detecting components 3 and 4 are amplified by the respective amplifying units 20 and 21.
2. When only the output of the light detecting component 4 is low, only this output is amplified by the associated amplifying units 20 and 21. In such case, depending on the necessity, the output of the light detecting component 3 may be attenuated by the amplifying unit 21.
3. The gains are to be set to such proper values that the respective outputs of the amplifying units 20 and 21 may become the same and, by comparing the values of those gains, the light transmittance of the lubricant 6 (the status of deterioration thereof) is to be estimated.
Even in the case of the lubricant deterioration detecting device 1, since the two light detecting components 3 and 4 are so arranged as to have their light detecting faces held displaced the distance d from each other relative to the direction of travel of the rays of light, the status of deterioration of the lubricant 6 can be detected without being adversely affected by thickness or light transmittance of the lubricant 6 itself, the intensity of the light source 2 and/or the distance from the light source to the light detecting components 3 and 4.
Even in the case of the lubricant deterioration detecting device 1, since the two light detecting components 3 and 4 are so arranged as to have their light detecting faces held displaced the distance d from each other relative to the direction of travel of the rays of light, the status of deterioration of the lubricant 6 can be detected without being adversely affected by thickness or light transmittance of the lubricant 6 itself, the intensity of the light source 2 and/or the distance from the light source to the light detecting components 3 and 4.
A twelfth preferred embodiment of the present invention will be described with particular reference to
It is to be noted that a temperature sensor 8 is provided in proximity of the free end of the bundled optical fiber array 10. Each of the bundles of optical fibers 11C and 12C is made up of a plurality of optical fibers, and a total light receiving surface area of one of the bundles of optical fibers 11C is chosen to be equal to that of the other of the bundles of optical fibers 12C. Except that the bundles of optical fibers 11C and 12C have respective free ends displaced from each other and also have respective base ends confronting the different detectors 11A and 12A, they are of the same construction.
For the light source 2, an LED, an incandescent bulb, a semiconductor laser diode, an EL, an organic EL or a fluorescent tube may be employed. Also, for each of the detectors 3 and 4, a photodiode, a phototransistor, a CDS, a solar cell or a photomultiplier may be employed. In
Also, the constant α in the equation (4) described previously varies depending on the status of the lubricant 6. By way of example, where the lubricant 6 is of a kind filled in the bearing assembly, foreign matter such as, for example, powdery wear debris are admixed into the lubricant 6 as the bearing assembly is used in practice and, accordingly, the constant α increases with an increase of the amount of the alien substance admixed. Also, oxidization and discoloring occur as deterioration of the lubricant proceeds and, therefore, where the lubricant 6 is a lubricating agent, the constant α increases as the lubricating agent is deteriorated. Accordingly, where the determining unit 5 determines the ratio between the signal strengths of the two detectors 11A and 12A, the light transmittance of light traveling the optical distance d in the lubricant 6 is measured and, therefore, based on the value of the detected output, the amount of the alien substance admixed in the lubricant can be estimated or the status of deterioration of the lubricant can be detected.
Even where in the determining unit 5, the difference between the respective signal strengths of the two detectors 11A and 12A is determined by means of the differential amplifier 16 as is the case with
As hereinabove described, this lubricant deterioration detecting device 1 is so designed that a bundled optical fiber array 10 is provided, which is made up of two bundles of optical fibers 11C and 12C having their free ends displaced a predetermined distance d from each other, in combination with the two detectors 11A and 12A connected with base ends of the optical fiber bundle 11C and base end of the optical fiber bundle 12C, respectively, also with the light source 2 positioned at a location confronting a free end of the bundled optical fiber array 10, while a position proximate to the free end of the bundled optical fiber array 10 and adjacent the light source 2 is chosen to be the site of the lubricant 6 so that the transmittance of the lubricant 6 can be measured by comparing, with the determining unit 5. Accordingly, the light transmittance of a lubricant 6 can be stably and accurately measured without being adversely affected by the thickness of the lubricant 6 itself the amount of the lubricant 6, the intensity of the light source 2 and the distance from the light source 2 to the detectors 11A and 12A. As a result thereof, even when the lubricant deterioration detecting device 1 is incorporated in, for example, the bearing assembly or the like, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited available space for installation. Also, considering that the light transmittance of the lubricant 6 is detected by comparing the respective signal outputs of the detectors 11A and 12A, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. In addition, since the bundled optical fiber array 10 is employed, a sufficient light receiving surface area can be secured on the light receiving side. For this reason, not only can a sufficient light receiving strength can be obtained with the detectors 11A and 12A, but any variation in thickness of the lubricant 6 brought about by the position can be cancelled and, therefore, a stable measurement of the light transmittance can be accomplished.
Also, with the determining unit 5 shown in
In addition, with the determining unit 5 shown in
Where the free end of the bundled optical fiber array 10 is planarly arranged to represent a planar shape, averaging can be made even though the distribution of thickness of the lubricant 6 varies and, therefore, a stable measurement can be accomplished without such variation adversely affecting the measured value. Also, merely positioning of the light source 2 (in
Where the two bundles of optical fibers 11C and 12C are arranged in line as described above, the light receiving unit can be constructed to have a thin structure and, therefore, the light transmittance of a lubricant 6 distributed in a planar shape can be measured. It is to be noted that even in this case, it is preferable to employ the light source 5 in the form having a linear shape so that the light receiving efficiency can be increased.
The rear lid 33 is mounted on a wheel axle 40 at a location closer to the midpoint thereof than the location of the bearing assembly 31 and has an outer periphery with which an oil seal 38 is slidingly engaged. The oil slinger 32 is mounted on the wheel axle 40 and has an outer periphery with which an oil seal 39 is slidingly engaged. The oil seals 38 and 39 arranged on opposite ends of the bearing assembly 31 serve to seal the lubricant within the bearing assembly 31 and, accordingly, the dust proofing and the resistance to water can be secured.
The lubricant deterioration detecting device 1 is fitted intermediate between the rows of raceway surfaces defined in the inner diametric surface of an outer ring 35 of the bearing device 31 for detecting the status of deterioration of the lubricant sealed within the bearing unit. The lubricant deterioration detecting device 1 is arranged in proximity to end faces of the rollers 36. The outer ring 35 is formed with a cable insertion hole 35a for passage therethrough of a wiring cable 19 of the lubricant deterioration detecting device 1, and a portion where the wiring cable 19 is inserted is treated to have a water resistance and an oil resistance. Through the wiring cable 19, an electric power supply from outside of the bearing to the lubricant deterioration detecting device 1 and transmission of the detection signal to outside of the bearing is carried out. In this way, any ingress of water and/or dusts into the bearing unit through an area where the lubricant deterioration detecting device 31 is fitted can be avoided.
In the detecting device incorporated bearing assembly 31 having the above described lubricant deterioration detecting device 1 mounted thereon, deterioration of the lubricant filled within the bearing unit can be accurately detected in real time or regularly. As a result, prior to an actual occurrence of an abnormality in the bearing device 31, the necessity of replacement of the lubricant can be judged and it is possible to prevent the bearing device 31 from being damaged as a result of the defective lubricant. Also, since the necessity of replacement of the lubricant can be determined in reference to the output of the lubricant deterioration detecting device 1, the amount of the lubricant which may be discarded prior to the life time of use can be reduced.
Hereinafter, a transmittance detecting device, which is an applied technology different in basic structure from the present invention will now be described.
The transmittance detecting device referred to above is so designed as to include a bundled optical fiber array made up of two bundles of optical fibers having their free end displaced relative to each other, with base ends of the optical fibers of the bundled optical fiber array connected with two light detectors one employed for each of the two bundles of optical fibers, a light source positioned in face-to-face relation with a free end of the bundled optical fiber array, and a determining unit for measuring the light transmittance of a sample by comparing signal outputs from the two light detectors, wherein a position adjacent the light source proximate to the free end of the bundled optical fiber array is chosen to be an area of placement of the sample.
In other words, the lubricant deterioration detecting device shown in and described with reference to
According to this construction, the amount of light attenuated after having passed across the thickness of the sample, which corresponds to the displacement in position of the free ends of the two bundles of optical fibers can be detected by comparison of the signal outputs from the two detectors. For this reason, without being adversely affected by the thickness of the sample itself, the amount of the sample, the intensity of the light source and the distance from the light source to the light detectors, the light transmittance of the sample can be stably and accurately detected. As a result thereof, even when the transmittance detecting device is incorporated in, for example, the bearing assembly or the like, the degree of freedom of arrangement comes to be high and construction is possible to accommodate to the limited available space for installation. Also, considering that the status of deterioration of the lubricant 6 is detected by comparing the respective signal outputs of the light detectors, a stable detection can be accomplished without being adversely affected by common mode noises such as a power source variation. In addition, since the optical fibers are employed and since a sufficient light receiving surface area can be secured on the light receiving side, not only can the intensity of received light be obtained with the light detectors, but also any variation in thickness of the sample depending on the position can be cancelled and, hence, even in this respect, the light transmittance can be stably measured.
Claims
1. A lubricant deterioration detecting device which comprises:
- a light source;
- a plurality of light detecting components for detecting rays of light emitted from the light source and subsequently transmitted through a lubricant, said plural light detecting components having respective light detecting faces sequentially displaced in position; and
- a determining unit operable to compare respective signal strengths of outputs from the plural light detecting components to thereby detect a status of deterioration of the lubricant.
2. The lubricant deterioration detecting device as claimed in claim 1, wherein the determining unit is of a type capable of estimating an amount of the alien substance admixed into the lubricant through comparison of the signal strengths.
3. The lubricant deterioration detecting device as claimed in claim 1, wherein each of the light detecting components includes a detector and a light guide element having one end in the form of a base end connected with the detector and the other end in the form of a free end forming the light detecting face.
4. The lubricant deterioration detecting device as claimed in claim 1, wherein each of the light detecting components includes a detector and an optical fiber having one end in the form of a base end connected with the detector and the other end in the form of a free end forming the light detecting face.
5. The lubricant deterioration detecting device as claimed in claim 1, wherein the light source is in the form of a linear-shaped light source.
6. The lubricant deterioration detecting device as claimed in claim 1, wherein the determining unit is of a type capable of calculating a light transmittance of the lubricant.
7. The lubricant deterioration detecting device as claimed in claim 1, wherein the determining unit includes a selector section for excluding, from the output signals of the plural light detecting components, output signals of a light detecting components which generate a saturated output, and output signals of light detecting components indicative of a detected light intensity not attaining a predetermined value, in order to use output signals of the rest of the light detecting components for detection of the status of deterioration of the lubricant.
8. The lubricant deterioration detecting device as claimed in claim 1, which includes two light detecting components.
9. The lubricant deterioration detecting device as claimed in claim 8, her comprising a temperature sensor positioned in proximity to the light detecting components.
10. The lubricant deterioration detecting device as claimed in claim 8, further comprising a light amount adjusting unit for adjusting an amount of light of the light source so that an output of one of the two light detecting components, which is closest to the light source, attains a predetermined constant value.
11. The lubricant deterioration detecting device as claimed in claim 8, further comprising a light amount adjusting unit for adjusting an amount of light of the light source so that an output of one of the two light detecting components, which is remotest from the light source, attains a predetermined constant value.
12. The lubricant deterioration detecting device as claimed in claim 8, further comprising an amplifying unit for amplifying an output of each of the light detecting components and a unit for adjusting a gain of the amplifying unit, wherein the determining unit compares the outputs amplified by the amplifying unit to detect the status of deterioration of the lubricant, and wherein the gain adjusting unit adjusts a gain of the amplifying unit to allow the output of each of the light detecting components, which has been amplified by the amplifying unit, to attain a value within a predetermined range.
13. The lubricant deterioration detecting device as claimed in claim 1 including two light detecting components, wherein each of the light detecting components includes a detector and a optical fiber bundle having one end in the form of a base end connected with a detector and the other end in the form of a free end forming a light detecting face.
14. The lubricant deterioration detecting device as claimed in claim 13, further comprising a temperature sensor positioned proximate to the free ends of the optical fiber bundles, and a correcting unit for correcting an output of the determining unit based on a detected value of the temperature sensor.
15. The lubricant deterioration detecting device as claimed in claim 13, wherein each of the respective free ends of the optical fiber bundles is arranged in line.
16. The lubricant deterioration detecting device as claimed in claim 15, wherein the light source is in the form of a linear-shaped light source corresponding to a line shaped arrangement of the free ends of the optical fiber bundles.
17. The lubricant deterioration detecting device as claimed in claim 13, wherein the optical fiber bundles have respective free end faces that are planarly arranged.
18. The lubricant deterioration detecting device as claimed in claim 17, wherein the light source is a planar light source corresponding to the planar shape in which the free ends of the optical fiber bundles are arranged.
19. A detecting device incorporated bearing assembly having mounted thereon a lubricant deterioration detecting device as defined in claim 1.
Type: Application
Filed: Jan 26, 2007
Publication Date: Feb 26, 2009
Patent Grant number: 8436292
Applicant: NTN CORPORATION (Osaka-shi)
Inventors: Toru Takahashi (Shizuoka), Akio Nakajima (Shizuoka)
Application Number: 12/162,294
